Electronic systems



Sept. 24, 1957 K, D vsMlTl-l- 2,807,712

ELEC'rRogJIc` SYSTEMS Filed Sept. 2, 1945 FIG. 2

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ATTORNEY y 21,807,712 fliiatented Sept. .24, `v1 957 2,807,712 ELECTRONICSYS'EEMS Kenneth D. Smith, :White-Plains, 1N. lY.,tassignor to Bell Telephone rLaboi-atories, Incorporated, New York, N. `Y.,at corporlitlll of New V:York

Application September 2, 19,43, Serial No.500,937 V11 Claims. .(61.5250-7) This invention relates to r electronic fsysterns Aand. more particularly to suchV a system 4adaptedto be controlled by radiant energy.

An objectof the inventionis to provideman improved radiant energy controlled electronic, system.

Another object of the inventiontis to provideA a radiant energy controlledsystem having aspace discharge device which is operated by suitable changes I.in the `received radiant `energy and having means to make said device responsive to progressively .smaller changes in the radiant energy during algiven time interval.

ln anexample of practice `of the invention an elec- `tronic system comprising aphotoelectric cell,a vacuum `tube -amplier and a thyratron `is arranged to detonate an explosive projectile. The function of the vsystem is to detect the presence of an object, such `as an airplane, in Yproximity 4,to the path of `travel of the projectile to which `it is attacheddueto an impulsive reduction in theamount of'lightincident on the Acell-and Vto cause the explosion of the explosive charge. Ifno Objectis encountered the explosive ,chargetis exploded independently of the photo- ,electric cellA before the projectile approaches Anear-enough to the earth to cause 'damageby its explosion. 'Precautions must be taken to prevent `premature,detonation before the projectile `hasirnoved f ar enoughawayfrorn tits handlers to prevent damage. ',These functions `are accomplished by applying automatically a Anegative Lblocking voltage tothe grid of thethyratron and,red u ci ng this voltage "at a predetermined rate until the thyratronires independently ofithe Vphotoelectric cell. The blocking voltage is applied through switch contacts which `are closed b yforces of acceleration duringthe initial stages of the projection of the projectile. A tsthe ,same ,time a condenser connected in a circuitbetween 4the grid and V,cathode of the thyratron is charged to the same voltage. 'When the acceleration `of the y,projectile falls below a rpredetermined value, as when the projectile approaches rthe V,target zone, the contacts open and Athe condenser begins to dischargethrough alarge shunting resistance, 4thereby reducing the negativebiasing ,Voltage `,on the grid of the thyratron. This negative biasing voltage approacheslztero on anexponential curve. Until the pro- Ijectile issprojected toward the target. zone this system .is `inoperative to effect detonation because 4power is not supplied to -the cathodes of the amplier tubes and the anodeof ,the thyratron. `vBy-this `arrangement the projectileis Iunarrrieddilring handlingand -for all practical 52 distance through the target lzone. Such advantage is obtained by applicants arrangement.

`In a modied `arrangement a `blocking voltage is also applied to'the grid circuit of one of the amplifier stages,

`which biasing `voltage is reducedmore rapidly than that on the thyratron. By this arrangementl the rate at which the projectile is armed and lthe time of self-destruction as `well as theeiectiveness of `the `disarming may better be controlled. Furthermore, a smallernegative voltage may be used to elect disarming.

This invention is useful for other 4purposes than the detonation of explosive projectiles. It is useful 4wherever indications of timed events are desired, which events are to occur within a predetermined time interval.

The invention `will now be described more in detail having reference tothe accompanying drawings.

Fig. 1 isa schematic circuit `arrangement of one embodiment of the invention.`

Fig. 2 `is a schematic circuit arrangement of a modied `embodiment ofthe invention.

Fig. 3 is a'graph showing thefreduction in light required 4to effect firing of the thyratron versus time after start of arming in the arrangement of Fig. 2.

The same reference characters are used to designate identical elementsin the `several figures of Athe drawing.

`Referring now to Fig. l, ,a circuitarrangement suitable vforheing housedn'ithin a container which is attached to an Aexplosive `projectile comprises a pho'toelectric cell 10, a three-stage vacuum tube amplier 11' `and `a thyratron stage T. The. output circnitof thyratron stage T .is coupled to a heater resistor 12 which may be used to ignite the detonating squibof the projectile. Energizing .currentis yfurnishedby a rbattery-,unit 113. The battery `unit 13comprises a lament heating battery ,14, `a plate batter-y 15, a negative biasingbattery condenser 17. ,The battery :13 is connected to the rest .ofthe circuit by meansof a multiple contact connector 18.

16 and a by-pass The vlltament heating circuitiscontrolled at contacts 19 of acceleration switch 20. The output circuit of thyratron stage T, including the load resistor 12, is controlled ,at contacts 21 of switch 2.0. The application of negative blocking voltage for the grid-filament circuit of thyratron stage T is controlled by contacts 22 of switch 20 which contacts may be closed by forces of accelera- `tion operating on Aa mass 23 mounted on `the relatively movable contact springof contacts `22.

T heinput stageVl of ampliiierll comprises vacuum tube .'24, input resistance 2S, plate resistance 26, and bypass 4condenser V27. The `intermediate stage V2 of amplier 11 comprises vacuumtube 28, input resistance 29 Vand plate resistance 30. The third or output stage V3 of amplifier lijcomprises vacuum tube 31, series input `resistance 32, shunt input `resistances 33 and 34, shunt condenser 35, input condenser 136 and .output resistances 37 `and 38. The thyratron` stageT comprises thyratron i tube 39, inputbiasing resistance 40, input condenser 41,

Mpurposes is unarmed during the early stages of itstravel toward the target zone. `During the time interval when it `is travelling through the target `zone,itbecornes sensitive to prpgressively smaller rchanges of Alight on thelphoto- .electric cell. finally, s oon afterit leaves the target zone Ithe `negative bias "has `:been Aso ,much reduced that the thyratron ,resand d etonates theprkojectile independently gf thephotoelectric cell. "For destructivelpurposes there is an alvantagesin requiring `,the projectile to approach clpserto a target to effect detonation as it enters the target zone, than after it has travelled a considerable lbiasing control condenser 42and discharge resistance 43. Theamplifier stages V1 and V2 `are coupled by condenser 44, stages VV2 and V3 by condenser 45 and stages V3 and Tby condenser 46. Thescreen grids of Vacuum tubes 28 and 31 are energized through resistances 47 and dll, respectively, from a portion `of battery 15 extending from `the grounded negativevterrninal 49 to the intermediate connection 50. The screen grid of `vacuum tube 2a is connected directly to theintermediate connection 50. The network 51 comprising condenser 42, .shunting resistance 43, negative biasing battery `16-andl contacts 22 of switch '20, functions according lto this invention to disarm -the projectile duringtheinitial stages of Aits `travel 'toward the Atarget-Zone, to arm "the projectile A-and make it operative cin-progressively smallerchangesoflight `as `it travels `through the target zone, and, Ylinally, `to cause the self-destruction ofthe projectile soon after it leaves the target zone if it has not previously been detonated by passing in proximity to a target.

The operation of the circuit of Fig.r l when usedto detonate an explosive projectile is briefly as follows.

f Vof switch 20 an the output circuit of thyratron stage T Yis open'between the load resistor 12 and the positive terminal of battery 1,5 at contacts 21 of switch 20. When lthe flight of the projectile begins, large forces due to acceleration are exerted on the ycam 52 causing it to move in a clockwise direction around the pivot 53 until the projection 55 comes against stop 57 The cam 52 is then held in this new position by the spring stop 54. In this new position contacts 19 and 21 are closed. At the same time forces of acceleration acting on mass 23 cause contacts 22 to be closed. Due to the closure of contacts 22 the negative voltage of battery 16 is impressed on the grid of thyratron tube 39 through resistance 40 and at the same time condenser 42 is charged to the full voltage of battery 16. This-voltage, if high enough, effectively blocks thyratron T and prevents firing of the thyratron no matter Whatchanges may occur in the illumination of` photoelectric cell 10. Since the thyratron T is blocked, the closure of thefilament heating circuit at contacts 19 and the thyratron output circuit through load resistance 12 at contacts 21 is merely to prepare the cir- Vcuit for subsequent use.V

When the acceleration drops below a predetermined value, as when the projectile approaches the target zone, contacts 22 are opened since the closing forces of acceleration on mass 23 are reduced. Condenser 42 begins to discharge through resistance 43 and the negative bias on the grid of thyratron 39 is reduced toward zero on an exponential curve represented (max.) is the voltage of battery 16 in volts, e the base of Naperian logarithms 2.71828,.t the time starting with the opening of contacts 22 in seconds, R the resistance of resistor 43 in ohms and C the capacity of condenser 42 in farads. The thyratron T can be tired under control of the photoelectric cell only when the negative biasing voltage of condenser 42 is overcome by the output voltage of amplitier stage V3 as it appears across condenser 41. With the arrangement of photoelectric cell 10 Vand three-stage amplifier 11 of Fig. l an impulsive re- Y .duction of light on the cell 10 makes the gridof thyra- 4tron 391 more positive. positiveimpulseis approximately constant for any given Furthermore, the value of this percentage reduction in light regardless of the static intensity of the light existing at the instant the reduction takes place due to the characteristics of the input circuit ol amplifier stage V1. Consequently, from the time contacts 22 areopened, progressively smaller vpercentages Vof light reduction are required to cause the -ring of thyratron T until finally the thyratron fires without any reduction inthe light as VWhen'the charge 'on condenser 42 approaches zero. Y w

From the foregoing brief description it is seen that the singlernetwork 51 in combination with the other elements of Fig. l accomplishes the functions of preventing Ypremature .detonation offtheV projectile during ordi'- .narr transiortatior-1v 4.and.11andl1-ina prevention of .Premature detonation during the early stages of 'travel toward where Ec is the voltage across condenser 42 in volts, Eo

the target zone in use, slow arming, gradual increasing of the sensitivity or reduction of the required percentage ot' light -reduction to re the thyratron and effecting selfd estruct1on. This circuit is much more simple than any c1rcu1t previously known for accomplishing similar functions.

A modified form of circuit arrangement generally similar lto that of F1g. l is illustrated Vin Fig. 2. The portion of the circuit tothe left of the lines X-X in Fig. 2 is identical with that to the left of the lines X--X in Fig. l. In the arrangement of Fig. 2 another set of contacts 60 is provided in switch 20. Contacts 60 are closed by forces of acceleration acting on mass 61 mounted on the relatively movable contact spring of contacts 60. The closure of `contacts 60 impresses negative biasing Voltage from battery 16 on the grid of vacuum tube 31 through resistances 32 and 33 in the input circuit of amplier stage V3 andV blocks Vthe amplifier at this stage. v Condenser 35 is simultaneously chargedto the same voltage. Contacts 60 are opened when the acceleration is reduced to a predetermined value, as when the projectile approaches the target zone. When the contacts 60 are opened condenser 35 begins to discharge through resistance 34 `and in a relatively short time removes completely the negative biasing voltage vfrom the grid of vacuum tube 31, thereby bringing the amplier 11 to full sensitivity.

The network 62 comprising condenser 35, shunting resistance 34, negative-biasing battery 16 and the contacts 60 of switch 20 functionstoblock ampliier stage V3 during the initial stages of the travel of the projectile Y toward the target zone and lto relatively slowly arm the system byV gradually restoring the ampliler to full sen-` sitivity. For a given value of negative biasing voltage from battery 16 more effective blocking may be obtained at the grid of amplier stage V3 than at thyratron stage T. ,Howeven if thyratron -stage T Vis to be red independerrtly of the photoelectric cell 10 the negative biasing voltage on the grid of thyratron T must be reduced. By

properly choosing the values of capacitance of condensers 42 and 35 and the resistance of resistances 43 and 34, the rate of arming, the rate of increasing the sensitivity and the time of self-destruction for any given voltage from battery 16 may be varied to suit the actual conditions of use. The'networks 51 and 62 of the arrangement of Fig. 2 cooperate to make this possible.,

fire the thyratron at the instant of opening contacts 22V and 60. For all practical purposes the firing of the thyratron T by the photoelectric cell 10 is blocked when contacts 22 and 60 are closed and for a second or two after they are opened.

To facilitate the practice of Vthis invention certain circuit constants Will now be given. It is to be understood, however, that these values are merely illustrative. The characteristics of Fig. 3 were obtained with the circuit arrangement of Fig. 2 by using the following circuit constants: a thyratron 39 which Vlires at approximately 2.5 voltsnegativev on the grid with a plate voltage of volts, ,photoelectric cell 10 and ampliier 11 which Vgives `a peak impulse across condenser 41 of l approximately 6 volts for a one per cent reduction in light on the cell 10, battery 16 of 9 volts, condenser 35 of 0.25

microfarad, condenser 42 of 0.25 microfarad, resistance anemia requiring widely different circuit constants than those given hereinbefore for purposesA of` illustration. The scope of the invention is delined by the accompanying claims.

What is claimed is:

l. electronic system comprising a space discharge tube having a cathode, an anode andl a controlv electrode, a load device connected between said cathode and anode and adapted to be operated by` space current flowing in said tube greater than a predetermined amount, a radiant energy sensitive device adapted when energized by radiant energy to cause space current-in said tube to operate saidload device when the bias on-` saidf control `electrode is within certain limits, a` circuit for placing a bias independently of'said radiant energy sensitive device on said control electrode including a condenser, means to charge said condenser to a potential which biases said control electrode to render said radiant energy sensitive )device ineiective to cause operation of said load device and a resistance shunting said condenser, and means to incapacitate saidcharging means allowing said condenser to slowly discharge through said resistance and reduce the bias on said tube whereby the load device will operate at the end of a given time interval if the radiant energy sensitive device is not energized during said interval and will operate sooner if and whenV the radiant energy sensitive device is energized within said'interval.

2. An electronic system comprising `a gaseous discharge tube having a cathode, an anode anda control electrode, a `load device connected between said cathode and anode and adapted to-be operated byspace'lcurrent flowing in said tube, a radiantenergy sensitive device adapted to control the iiow of space current in said tube when the bias on said control electrode is within denite limits, and means comprising a condenser shunted by a resistance for placing a bias on the control electrode of said tube which bias at first prevents flow of space current in said tube regardless of the action of said radiant energy sensitive device, then is` within said definite limits and inally causes flow of space currentindependently of said radiant energy sensitive device,said condenser being so connected in a circuit between said cathode and control electrode that its voltage is independent of vthe space current in said tube.

3. An electronic system comprising a gaseous discharge tube having a cathode, an anode and a control electrode, a load device connected between said cathode and anode and adapted to be operated by space current owing in said tube, a radiant energy sensitive device adapted to control the flow of space current in said tube when the bias on said control electrode is within definite limits, means comprising a condenser shunted by a resistance for placing the said bias within said limits for a definite period of time, and means including relatively movable contacting members for charging said condenser temporarily to a potential to bias said control electrode to prevent flow of space current in said tube regardless of the action of said radiant energy sensitive device.

4. An electrical control unit for use with an element designed to be given accelerated motion in a medium capable of transmitting wave energy comprising a device sensitive to radiations transmitted through said medium, a voltage controlled space current discharge device having said radiation sensitive device in its input circuit and having space current flowing therein in the absence of blocking potential in said input circuit, and means operable to apply blocking potential to said input circuit by forces resulting from the movement of said unit in a predetermined direction at a predetermined acceleration including means to remove said blocking potential slowly whereby the ow of space current is first brought under control of said radiation sensitive device and then made independent of said device.

5. An electronic system comprising a vacuum tube having a cathode, an anode and a control electrode, a

load device connected between `said anode and cathode which is operated only when the voltage `between said cathode and control electrode is small, a condenser shunted by a resistance connected in circuit between said cathode and control electrode, a source of direct current, connections between said condenser and` said source to charge said condenser and negatively `bias said control electrode with respect to said cathode, including meansto open said charging circuit to permit said condenser to discharge slowly through said resistance causing saidload device. to operate after a fixed period when the. charge on said condenser is reduced by a given amount, and a radiant energy sensitive device connected tosaid cathode and control electrode to quickly change the voltage on said control electrode in the same direction that the discharge of said condenser changes said -voltage when energized by radiations, whereby said device will operate at the end ofk a given time interval if said radiant energy device is not energized and will operate sooner iiand when said radiant energy device ist energized.

6. An electrical control system comprising a radiant .energy sensitive device, a vacuum tube amplifier having an input circuit connected to said device :and an output circuit, a thyratron having an input circuit connected to the output circuit of said amplifier and an output circuit; a biasing network comprising al condenser shunted by a resistance connected across the input circuit of said thyratron, and means independent of the output circuit of 'said thyratron to charge saidcondenser to negatively bias said thyratron to effectively prevent firing thereof by said radiant energy sensitive device and to discharge said condenser through said resistance.

7; yAn electrical control system comprising a radiant energy sensitive device, a vacuum tube amplifier having an input circuit connected to said d'evice and an` output circuit, a thyratron having an input circuit connected to the output circuit of said amplier andan `output circuit, a biasing network comprising a condenser shunted by a resistance connected across the input` circuit of said thyratron, a second biasing network comprising another condenser shunted by another resistance connected across the input circuit of one stage of said ampliiier, and means to charge said condensers toinegatively bias said amplifier stage and said thyratron to effectively pre-vent ring of said thyratron by said radiant energy sensitive device and to discharge said condensers through said resistances respectively.

8. An electrical control system comprising a radiant energy sensitive device, a v-acuum tube amplifier having an input circuit connected to said device and an output circuit, a thyratron having an input circuit connected to the output circuit of said amplifier and an output circuit, a condenser connected across the input circuit of said thyratron, a biasing battery, a switch adapted when closed to connect said battery to said condenser to negatively bias said thyratron to render said radiant energy sensitive device ineffective to cause firing of said thyratron, and a resistance connected in shunt of said condenser adapted to discharge said condenser after the opening of said switch at a rate which is first rapid and then slow until the thyratron tires provided the thyratron has not previously been iired by a radiant energy impulse received by said radiant energy device.

9. An electro-optical system comprising a vacuum tube amplifier stage including a vacuum tube having a cathode, an anode, and a control electrode, a thyratron having a cathode, an anode, and a control electrode, a condenser-resistance coupling between the anode-cathode circuit of said vacuum tube and the control electrodecathode circuit of said thyratron, a photoelectric cell coupled to the control electrode-cathode circuit of said vacuum tube for impressing electrical impulses on said circuit corresponding to light impulses on said cell, a first biasing network comprising a condenser shunted by a resistance connected between the control electrode and Y A7 cathode ofsaid thyratron, a seco'ndbiasing network also comprising aV condenser shunted by' a resistance connected between the control electrode and cathode of said vacuum tube, the ratio 'of the time constant-of said rst networkto.

ythe time constant of said second network being of 'the order-of ten, and means for charging the condensers of both said networks to negatively bias said control electrodes, respectively, to practicallyprevent firing of said thyratron by light impulses until such time as it is desired to make the Circuit responsive'to light impulses and then allowing said condensers to discharge `through said resistances respectively. t Y

y 10. An electro-optical system comprising a vacuum tube amplifier stage including a vacuum tube having a cathode,;an anode and a controlelectrode, a thyratron having a cathode, an anode, and a control electrode, a condenser-resistance coupling between the anode-cathode circuit of said vacuum tuberrand the control electrodecathode circuit of said thyratron, a photoelectric cell coupled to the control 'electrode-cathode circuit of said vacuumtube for impressing electrical impulses on said circuit corresponding toylight impulses on said cell, ab

cathode energizing battery, an anode battery, a grid biasing battery, said cathode and `anode batteries havingV their negative terminals and said grid battery having its positiveterminal connected to the cathodes of said vacuum i tube Vand thyratron, switch contacts operated by forces of acceleration forv connecting the positive terminal of said cathode energizing battery to said cathodes, other switchcontacts Aalso operated by the sameforces of acceleration vfor connecting the positive terminal of said anode'battery through a load device tothe anode of said thyratron, a network comprising a condenser and shuntingV resistance connected in circuit between the grid and cathode of said thyratron and a third set of switch con- .tacts connecting the negative terminal of said grid biasing battery to the, grid terminal of said network only so long as theacceleration exceeds a predetermined value.

`I11.,An,electrooptical system comprising a vacuum tube amplifier stage including a vacuum tube having a cathode, .an anode and a control electrode, Va thyratron having a cathode, lan anode, `and a control electrode, a condenser-resistance coupling between the anode-cathode circuit of said Vacuum tube and the control electrodenegative` terminals and said gridV battery having its posi-` tive terminal connected to the 'cathodes of saidvacuum tubev andthyratron,rswitch contacts operated by forces of acceleration for connectingthe positive terminal of the cathode energizing battery to said CathOdeS, other switch contacts also operated by the same forces of acceleration for connecting the positive terminal of said anode battery through aload device lto the Vanode of said thyratron,

a networkcomprising a condenser and shunting resistance Yconnected in circuit between the4 grid and cathode of said thyratronvand agthird set of switch contacts-connecting the negative ,terminal of said grid biasing battery to the grid terminal of'said network only so long as the V acceleration exceeds Ya predetermined value, va second network comprising anothenondenser Vand shunting resistance connected in circuit between'the grid and cathode of said yacuum tube anda fourth set of switch contacts` connecting the negative terminal o fV Vsaid grid biasing battery to the grid terminal of said sec-ond network only so long as the acceleration exceeds said predetermined value.V

References Cited in the me of this patent UNITED STATES PATENTS 1,819,999 Kearsley ..V Aug. 18, 1931 1,841,983 i Ruhlemann Jan.. 19, 1932 1,988,274 '-Glazer Jan. 15, 1935 2,009,459` Turner July 30, 1935V 2,164,916 Hammond Iuly 4, 1939 2,167,492 Y Sproule July 25, 1939 2,255,245 Ferrel Sept. 9, 1941 2,270,773 Sonnentag et al. Jan. 20, 1942 27,274,992 Nelsen Mar. 3, 1942 V2,284,850 Smith June 2, 1942 v 2,288,554 Y Smith June 30, 1942 2,313,101 Stuart' Mar. 9, 1943 FOREIGN PATENTS 376,987 1939 

